High pressure safety valve

ABSTRACT

A high pressure safety valve which automatically closes when high pressure conditions exist. The high pressure valve includes a diaphragm valve and a snap acting assembly connected to the diaphragm valve which acts to snap it closed when a high pressure condition is detected. The safety valve of the present invention may also include a relief valve which opens when the diaphragm valve closes to relieve pressure at the outlet of the safety valve. In addition, the safety valve of the present invention can be manually reset only after the high pressure condition has been corrected.

BACKGROUND OF THE INVENTION

In the prior art, LP gas supply systems for motor homes, recreationalvehicles, and other places have generally included the storage tanksupplying gas at high pressures, a pressure regulator downstream fromthe storage tank which steps down and regulates the pressure at a usablelevel, and the appliances downstream from the pressure regulator. It ispossible that the pressure regulator in such systems can fail, thussupplying LP gas to the appliances at storage tank pressures. It isevident, therefore, that the failure of the pressure regulator in LP gassystems, creates a very dangerous condition and that protection againstpressure regulator failure is certainly desired in such systems.

High pressure safety valves have been developed in the past which arelocated between the pressure regulator and the appliances in an LP gassystem. Generally speaking, the prior art high pressure safety valveshave been satisfactory in many respects, but at the same time they haveproved to be disadvantageous in many respects also. Generally speaking,the prior art devices are slow acting, expensive to manufacture and havenot provided certain advantageous features. While most of the prior arthigh pressure safety valves have been manually resettable, many of themallow the person resetting them to open the safety valve, even if thehigh pressure condition still exists. In addition, the prior art devicesallow the high pressure to remain at the outlet of the safety valve,even after the valve has closed. Thus, while the prior art devices haveprevented the flow of LP gas after the safety valve has closed, it ispossible for a high pressure condition to remain at the input to theappliances.

SUMMARY OF THE PRESENT INVENTION

It is an object of the present invention to provide a high pressuresafety shut off valve which obviates the disadvantages of the prior artsafety shut off valves. More specifically, it is an object of thepresent invention to provide a high pressure safety shut off valve whichis fast acting, simple and inexpensive to construct. It is an additionalobject of the present invention to provide a manually resettable highpressure safety valve, which cannot be reset while the high pressurecondition continues to exist. It is a further object of the presentinvention to provide a high pressure safety shut off valve which inaddition to closing when a predetermined pressure is reached, alsorelieves any high pressure conditions existing at the outlet wheneverthe safety valve is closed.

These objects are accomplished by a high pressure safety valve having adiaphragm operated main valve which responds to differentials betweenthe outlet pressure and a reference pressure and a spring toggleassembly operatively connected to the main diaphragm valve such that thevalve closes with a snap action when the outlet pressure reaches apredetermined level. A safety valve of the present invention may alsoinclude a manual means for resetting it in the form of a push buttonwhich compresses a compression spring against the diaphragm so as tourge the main valve in the open direction. The extent of travel of thepush button is limited by an abutment in the housing such that thespring can only be compressed to a certain degree. If the inlet pressureon the main diaphragm valve is too great, the force exerted on the valveby the push button spring does not overcome this force to open thevalve. The safety valve of the present invention also preferablyincludes a relief valve which opens whenever the main valve is closedand the pressure in the outlet of the safety valve is above apredetermined level to relieve the outlet pressure.

The above objects as well as further objects will become apparent fromthe following detailed description of the present invention taken inconjunction with the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a high pressure safety valve inaccordance with the present invention shown in the open position;

FIG. 2 is a cross sectional view of the same high pressure safety valve,except that it is shown in the closed position with the relief valveclosed; and

FIG. 3 is a cross sectional view of the same high pressure safety valveshown in the closed position with the relief valve open.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE PRESENTINVENTION

Referring now to FIG. 1 a high pressure safety valve 10 in accordancewith the present invention is shown in the open position. The housingfor this valve preferrably includes a first section 12 which includes aninlet 14, and an outlet 16 which are both internally threaded so thatthe valve 10 may be suitably connected into an LP gas system. Inaddition, the housing section 12 includes a valve seat 18 locatedbetween the inlet 14 and the outlet 16.

A second housing section 20 has an annular downwardly extending sidewall22 which is adapted to mate with an annular upwardly extending sidewall24 on housing section 12. When the housing sections 12 and 20 aresecured together by cap screws or other suitable means, a chamber isformed which is divided by a movable wall diaphragm member 26 to form achamber 28 which communicates with outlet 16 and an upper or controlchamber 30 which is vented to the atmosphere through passageway 31. Itwill be seen that the peripheral edge of the diaphragm member 26 isclamped between sidewalls 22 and 24, thus ensuring that chambers 28 and30 are sealed from one another and that chamber 28 is sealed from theatmosphere. The diaphragm assembly also includes plates 32 and 34 whichare held in place on opposite sides of the diaphragm 26 between the cap36 of a hollow screw member 38 and the enlarged end portion 40 of ahollow guide member 42 into which the screw 38 is threaded. A valve stem44 extends axially into the bore of screw member 38, through thediaphragm 26 and into the guide 42. The valve stem 44 includes a recessnear the end which receives a valve 46 adapted to cooperate with valveseat 18. Valve stem 44 also includes a second ring-like recessintermediate its ends which receives an O-ring 48. The top end of valvestem 44 is threaded so as to receive a corresponding threaded springretainer 50. Thus, spring retaining cap 50 acts to retain a relief valvespring 52 in place between the cap 50 and into a ledge 54 whichprotrudes into the bore of guide 42. It will therefore be seen thatrelief valve spring 52 acts to urge valve stem 44 upwardly relative toguide 42 so as to urge O-ring 48 closed. It will also be seen thatO-ring 48 essentially forms a relief valve in which the chambers 28 and30 are connected together when the relief valve is open.

A reset compression spring 56 is located between an outwardly extendingledge 60 on the guide 42 and a pushbutton member 58 so that downwardmovement of the push button 58 compresses the reset spring 56, which inturn, urges the guide 42 and the main valve 46 toward the open position.It will be seen that the downward extent of movement of the reset button58 is limited by a flange 62 extending inwardly from the housing section20.

A snap acting operator includes a flat pivoted arm 64 in the chamber 30having a first end 66 located between a protrusion 68 on the inside ofthe upper housing and an upwardly extending pivot 70 to form a fulcrumpoint for the arm 64. A pair of tabs (not shown) on the arm 64 arereceived in a pair of corresponding pair of notches (not shown) on theguide 42 so that the guide is moved up and down as the arm 64 is movedand vice versa. The snap acting assembly also includes a compressionspring 72 compressed between the second end 74 of the arm 64 and springretainer 76 having a socket 78 which rotates on an adjustable ball 80.

The housing also includes a third section 82 which is threaded intohousing section 20. The cap or housing section 82 is preferably moldedfrom a transparent material such as LUCITE or other suitable material.Preferably, the top of reset button 58 may carry a suitable legendthereon such as "OFF" and the cap 82 may be molded so that the cap 82magnifies the legend in such a manner that the legend is in focus whenthe push button 58 is in the off position and that the legend is not infocus when the push button is in the on position. In this manner, avisual indication is given as to the condition of the high pressure shutoff valve.

The operation of the high pressure shut off valve in accordance withpresent invention will be described in conjunction with FIGS. 1, 2 and3.

The valve is shown in FIG. 1 in the open position. In this position, itwill be appreciated that the downward forces on the diaphragm 26 (thepressure in chamber 30, the weight of the various components acting onthe diaphragm and the vertical component of the force exerted on arm 64by spring 72) are greater than the upward forces exerted on thediaphragm (the pressure in chamber 28) so that the valve 46 is moved toits open position.

If an abnormal condition is created upstream of the shut off valve, suchas a pressure regulator diaphragm rupturing, the pressure at the outlet16 and thus chamber 28, increases to the point where the upward anddownward forces exerted on the diaphragm are equal. Eventually, when thecombined upward forces only slightly exceed the combined downward forceson the diaphragm, the snap acting assembly will overcenter and pull themain valve 46 closed as shown in FIG. 2. The automatic high pressuresafety shut off valve will then remain in the position shown in FIG. 2with the main valve 46 and the bleed valve 48 closed unless the outletpressure increases or the valve is manually reset as will hereinafter bedescribed. Of course, as soon as the main valve 46 closes, the pressureon the inlet side of the main valve provides an upward force on thevalve 46 and thus, diaphragm 26. Therefore, in the position shown inFIG. 2, the net resultant force on the diaphragm 26 is in the upwarddirection.

As was mentioned above, the purpose of the push button 58 is so that thehigh pressure safety valve can be manually reset after it has closed dueto a high pressure condition only after the abnormal condition has beenremoved. In order to reset the high pressure safety valve of the presentinvention, it is necessary to provide a downward force on the diaphragmwhich exceeds the net force on the diaphragm. Inasmuch as the net forceon the diaphragm is in the upward direction and increases as the inletpressure increases, provision is made so that the downward reset forcecannot open the main valve 46 in the event the inlet pressure is above apredetermined level. Referring to the drawings it will be seen that bydepressing push button 58 reset spring 56 is compressed, thus providingthe downward reset force on the diaphragm. Further, inasmuch as theabutment 62 limits the downward movement of the push button 58 (and thusthe amount of compression of spring 56), it will be appreciated that thereset force cannot exceed a predetermined level. Therefore, the devicecannot be reset as long as the inlet pressure is above a predeterminedlevel.

In FIG. 3, the device is shown with the main valve 46 closed and therelief valve 48 open. The purpose of the relief valve is to prevent theoutlet pressure from rising above a certain level when the main valve isclosed. Such a condition can occur if the main valve leaks slightly.Under this condition the outlet pressure can build up to a potentiallydangerous level. Referring now to FIG. 3, it will be seen that if thepressure increases in the outlet chamber 28 while the main valve 46 isclosed, the biasing on the diaphragm 26 will be upset, resulting in anupward movement of the diaphragm. The upward movement of the diaphragmpulls head 36 of screw member 38 away from O-ring relief valve 48creating a vent for the pressure in chamber 28. As gas is bled off fromthe outlet chamber 28 along the path indicated by the arrows in FIG. 3,it will be appreciated that the pressure therein will remain at a verylow, substantially constant level.

It will be appreciated by those skilled in the art that theabove-described safety shut off valve provides a device which closesquickly and precisely as soon as the inlet pressure rises to apredetermined level. In addition, the above-described device because ithas the novel relief valve structure, provides an even greater degree ofsafety than that provided by prior art devices. Further, inasmuch as theabove-described device can only be reset when the inlet pressure isbelow a safe level, an additional degree of safety is provided.

Since obvious variations will occur to those skilled in the art, it isintended that the above detailed description of the invention be usedfor exemplary purposes only. The invention is defined in the claims.

What is claimed is:
 1. A high pressure safety valve, comprising:ahousing having an inlet, an outlet and a main passageway connecting saidinlet and said outlet; main valve means .Iadd.movable between closed andopen positions .Iaddend.disposed in said main passageway for controllingflow therethrough; differential pressure responsive means operablyconnected to said valve means for moving said main valve means towardand away from the closed position in response to differentials inpressure between a reference pressure and the pressure at said outlet;snap acting operator means comprising a pivoted arm member andovercentering spring biasing means operatively connected to saiddifferential pressure responsive means for moving said main valve meansfrom the closed position to the open position, and vice versa, with asnap action when the differential pressure responsive means moves.Iadd.said main valve means .Iaddend.in a direction from the .[.close.]..Iadd.closed .Iaddend.position to the open position, and vice versa; andrelief valve means operated by said differential pressure responsivemeans for relieving the pressure at said outlet whenever said outletpressure rises above a predetermined level and said main valve is.Iadd.in said .Iaddend.closed .Iadd.position. .Iaddend.
 2. The highpressure safety valve as claimed in claim 1, wherein:said differentialpressure responsive means comprises a diaphragm in said housingseparating a control chamber connected to the atmosphere from a pressurechamber communicating with said outlet; guide means having alongitudinally extending bore therein is attached to said diaphragm;said main valve means comprises a valve member attached to one end of avalve stem, said valve stem being of smaller diameter than said bore andextending axially into said bore so as to allow the passage of gasthrough said bore between said outlet and said control chamber; O-ringrelief valve means surrounding said valve stem adapted to shut off thepassage of gas between said outlet and said control chamber; and springmeans compressed between said guide member and said valve stem forbiasing said relief valve closed, the bias force provided by said springmeans being overcome when said main valve is .Iadd.in said.Iaddend.closed .Iadd.position .Iaddend.and the pressure in said outletexceeds a predetermined level to open said relief valve and vent thepressure in the outlet to the atmosphere through said control chamber.3. The high pressure safety valve as claimed in claim 1, furthercomprising:means for manually resetting said safety valve once said mainvalve .Iadd.means .Iaddend.has .Iadd.moved to said .Iaddend.closed.Iadd.position.Iaddend.; and means for preventing said safety valve frombeing reset when the inlet pressure is above a predetermined level. 4.The high pressure safety valve as claimed in claim 3, wherein said meansfor manually resetting said safety valve comprises:a push button; springmeans operatively located between said differential pressure responsivemeans and said push button for providing a reset force on said pressureresponsive means and consequently on said main valve .Iadd.means.Iaddend.to .[.open.]. .Iadd.move .Iaddend.said main valve .Iadd.meansto said open position .Iaddend.when said push button is depressed; andabutment means on said housing for limiting the extent of movement ofsaid push button and consequently for limiting the reset force so thatsaid main valve can only be reset when the inlet pressure on said mainvalve is below said predetermined level.
 5. A high pressure safetyvalve, comprisinga housing having an inlet, an outlet and a mainpassageway connecting said inlet and said outlet; main valve means.Iadd.movable between closed and open positions .Iaddend.disposed insaid main passageway for controlling flow therethrough; differentialpressure responsive means operably connected to said valve means formoving said main valve means toward and away from the closed position inresponse to differentials in pressure between a reference pressure andthe pressure at said outlet; snap acting operator means comprising apivoted arm member and over centering spring biasing means operativelyconnected to said differential pressure responsive means for moving saidsaid main valve means from the closed position to the open position, andvice versa, with a snap action when the differential pressure responsivemeans moves .Iadd.said main valve means .Iaddend.in a direction from theclosed position to the open position and vice versa; means for manuallyresetting said safety valve once said main valve .Iadd.means.Iaddend.has .Iadd.moved to said .Iaddend.closed.Iadd.position.Iaddend.; and means for preventing said safety valve frombeing reset when the inlet pressure is above a predetermined level.